Ball point pens are available in a wide variety of types and prices, from expensive pens with replaceable cartridges to low-cost stick pens.
A disadvantage of a stick pen is that its cap is easily misplaced. A further disadvantage is that its narrow width makes it less comfortable to write with than a wider pen.
A disadvantage of a pen with a replaceable cartridge is that the cartridges are relatively expensive to replace. Further, since each cartridge is designed for use with a specific type of pen, the cartridges may not be widely available.
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the present invention.